Scrambling-induced entanglement suppression in noisy quantum circuits

TL;DR

This paper studies how dephasing noise impacts quantum information scrambling and entanglement in noisy quantum circuits, revealing regimes of entanglement generation and suppression, with implications for quantum device design.

Contribution

It demonstrates the noise-sensitive nature of quantum scrambling and identifies distinct entanglement regimes, highlighting the limitations of current noisy quantum devices for long-range information exchange.

Findings

Scrambling enhances information distribution but is highly noise-sensitive.

Two entanglement regimes: efficient under weak noise, suppressed under strong noise.

Entanglement suppression occurs when noise exceeds the scrambling's entanglement creation capacity.

Abstract

Quantum information scrambling is a process happening during thermalization in quantum systems and describes the delocalization of quantum information. It is closely tied to entanglement, a key resource for quantum technologies and an order parameter for quantum many-body phenomena. We investigate the effect of dephasing noise on a multi-qubit teleportation protocol that experimentally validated quantum information scrambling. We find that while scrambling enhances information distribution, it is highly noise-sensitive, leading to decreased teleportation fidelity and an increase in the classical mixing of the quantum state. Using negativity as a mixed-state entanglement measure, we identify two fundamentally different entanglement-scaling regimes: efficient entanglement generation under weak dephasing noise, and entanglement suppression under strong dephasing noise. We show that in the latter, the teleportation consumes more entanglement than the scrambling is able to create. Comparison with a SWAP-gate-based teleportation protocol confirms that the entanglement suppression is a consequence of the scrambling mechanism. Our findings suggest that the information dynamics during thermalization is critically affected by dephasing noise, and confirm that in present-day noisy quantum devices, local information exchange is preferable over long-range information scrambling.